1 .The respiratory center consists of a medullary respiratory center in the medulla and a pontine respirator group in the pons.

2. The medullary respiratory center in the medulla is made up of a dorsal respiratory group (DRG), which controls normal quiet breathing, and a ventral respiratory group (VRG), which is used during forceful breathing and controls the rhythm of breathing.

3. The pontine respiratory group in the pons may modify the rhythm of breathing during exercise, speaking,and sleep.

4. The activity of the respiratory center can be modified in response to inputs from various parts of the body in order to maintain the homeostasis of breathing.

5. These include cortical influences; the inflation reflex; chemical stimuli, such as O2 and CO2 and H_levels; proprioceptor input; blood pressure changes; limbic system stimulation; temperature; pain; and irritation to the airways.